The present application claims foreign priority under 35 USC 119 based on Japanese application no. 2004-179791, filed on Jun. 17, 2004, the contents of which is incorporated herein by reference. This priority claim is being made concurrently with the filing of this application.
The present invention relates to a linear guide bearing apparatus used in a machine tool, a semiconductor fabricating apparatus or the like of a machine element part for guiding a linearly moving body.
There is a generally used linear guide bearing apparatus described in, for example, Patent Reference 1. As shown by FIG. 14, the linear guide bearing apparatus 1 is provided with a guide rail 2, and a slider 4 riding over the guide rail 2 movably relative to each other.
Each of both slider faces of the guide rail 2 is formed with two rows of rolling member rolling grooves 6 extended in an axial direction.
The slider 4 comprises a slider main body 8 and end caps 10 respectively joined to both end faces in the axial direction of the slider main body 8. As shown by FIG. 15, inner side faces of both sleeve portions of the slider main body 8 are respectively formed with rolling member rolling grooves 16 opposed to the rolling member rolling grooves 6 of the guide rail 2, and a load rolling path 14 is constituted from an interval between the two rolling member rolling grooves 6, 16. Further, thick wall portions of the both sleeve portions are respectively formed with two rows of rolling member return paths 24.
The load rolling path is rollably charged with a plurality of cylindrical rollers 18 as rolling members, and the slider 4 is made to be movable along the axial direction on the guide rail 2 relative to each other by way of rolling of the cylindrical rollers 18.
When the slider 4 is moved, the plurality of cylindrical rollers 18 charged to the load rolling path 14 are moved to an end portion in the axial direction of the slider 4 while being rolled. Therefore, in order to continuously move the slider 4 in the axial direction, it is necessary to infinitely circulate the plurality of cylindrical rollers 18.
Therefore, by forming a direction change path communicating between the load rolling path 14 and the rolling member return path 24, there is formed a rolling member rolling path for infinitely circulating the plurality of cylindrical rollers 18.
As shown by FIG. 16, the end cap 10 is constituted by an end cap main body 44 and a fit-to-insert member 90. Further, by providing an opening portion at a face of the end cap main body 44 for joining with the slider main body 8 and fitting the fit-to-insert member 90 to the opening portion, an inner side direction change path 50 and an outer side direction change path 60 are formed.
As shown by FIG. 17, the inner side direction change path 50 is constituted by an inner peripheral guide face 52 and an outer peripheral guide face 56 opposed to a rolling face of the cylindrical roller 18, and a middle guide face 54 opposed to an end face of the cylindrical roller 18. Also the outer side direction change path 60 is similarly constituted by an inner peripheral guide face 62 and an outer peripheral guide face 66 opposed to the rolling face of the cylindrical roller 18, and a middle guide face 64 opposed to the end face of the cylindrical roller 18. The inner side direction change path 50 and the outer side direction change path 60 are intersected by each other in a crossing shape, and communicate between the load rolling paths 14 and the rolling member return paths 24 different from each other.
[Patent Reference 1]
JP-A-Hei4-366016
However, according to the linear guide bearing apparatus 1 having the above-described constitution, a connecting portion 92 for connecting the end cap main body 44 and the fit-to-insert member 90 is formed at the middle guide face 54 and the outer peripheral guide face 56 of the inner side direction change path 50. Further, when a stepped difference is produced at the connecting portion 92 by an error in molding the end cap main body 44 and the fit-to-insert member 90 or the like, smooth circulation of the cylindrical roller 18 is hampered and therefore, operability of the linear guide bearing apparatus 1 is deteriorated. Particularly, when the stepped difference is produced at the connecting portion 92 formed at the middle guide face 54, a problem of catching the end face of the cylindrical roller 18 by the stepped difference or the like is posed and therefore, the operability of the linear guide bearing apparatus 1 is further deteriorated.
Such a problem can be prevented by molding the end cap main body 44 and the fit-to-insert member 90 with high accuracy or promoting accuracy of attaching the fit-to-insert member 90 to the end cap main body 44. However, the end cap main body 44 and the fit-to-insert member 90 are fabricated by injection molding and therefore, deformation is frequently brought about by a sink mark in molding or the like and it is difficult to mold the end cap main body 44 and the fit-to-insert member 90 with high accuracy. Further, there is a limit also in promoting the accuracy for attaching the fit-to-insert member 90 to the end cap main body 44 and it is difficult to firmly prevent the stepped difference from being produced to the connecting portion 92.